On Tue, Oct 17, 2023 at 2:27 AM Sivaprasad Tummala
<sivaprasad.tumm...@amd.com> wrote:
>
> Add eventdev support to enable power saving when no events
> are arriving. It is based on counting the number of empty
> polls and, when the number reaches a certain threshold, entering
> an architecture-defined optimized power state that will either wait
> until a TSC timestamp expires, or when events arrive.
>
> This API mandates a core-to-single-port mapping (i.e. one core polling
> multiple ports of event device is not supported). This should be ok
> as the general use case will have one CPU core using one port to
> enqueue/dequeue events from an eventdev.
>
> This design is using Eventdev PMD Dequeue callbacks.
>
> 1. MWAITX/MONITORX:
>
> When a certain threshold of empty polls is reached, the core will go
> into a power optimized sleep while waiting on an address of next RX
> descriptor to be written to.
>
> 2. Pause instruction
>
> This method uses the pause instruction to avoid busy polling.
>
> Signed-off-by: Sivaprasad Tummala <sivaprasad.tumm...@amd.com>
Hi Siva,
It does not look it is aligned with previous discussion.
I spend a couple of minutes to draft semantics. Please treat as reference.
# IMO, only following public SLOW PATH eventdev API required.(Just
share the concept)
enum rte_event_pmgmt_modes {
/** Default power management scheme */
RTE_EVENT_POWER_MGMT_TYPE_DEFAULT;
/** Use power-optimized monitoring to wait for incoming traffic */
RTE_EVENT_POWER_MGMT_TYPE_F_CPU_MONITOR = RTE_BIT(0),
/** Use power-optimized sleep to avoid busy polling */
RTE_EVENT_POWER_MGMT_TYPE_F_CPU_PAUSE = RTE_BIT(1),
/** HW based power management scheme found in ARM64 machines,
where core goes to sleep state till event available on dequeue */
RTE_EVENT_POWER_MGMT_TYPE_F_HW_WFE_ON_DEQUEUE = RTE_BIT(2),
};
int rte_event_port_pmgmt_type_supported_get(uint8_t dev_id, enum
rte_event_pmgmt_modes *mode_flags)
/** Device must be in stop state */
int rte_event_port_pmgmt_enable(uint8_t dev_id, uint8_t port_id, enum
rte_event_pmgmt_modes mode);
int rte_event_port_pmgmt_disable(uint8_t dev_id, uint8_t port_id);
# It should be self-contained, No need to add to rte_power as it is
CPU only power mgmt.(See RTE_EVENT_POWER_MGMT_TYPE_F_HW_WFE_ON_DEQUEUE
above)
# Add: lib/eventdev/eventdev_pmd_pmgmt.c or so and have CPU based on
power management helper functions
so that all SW PMD can be reused.
example:
eventdev_pmd_pmgmt_handle_monitor(uint8_t dev_id, uint8_t port_id,
struct rte_event ev[], uint16_t nb_events);
eventdev_pmd_pmgmt_handle_pause(uint8_t dev_id, uint8_t port_id,
struct rte_event ev[], uint16_t nb_events);
# In rte_event_dev_start(), Fixup dev->dequeue_burst if CPU based
power management is applicable,and it is selected.
ie. new dev->dequeue_burst is existing PMD's dev->dequeue_burst +
eventdev_pmd_pmgmt_handle_.. (based on power management mode selected)
